lets say I go to the local building supply store and buy a fixture for a security light. and it comes with a merc. vapor bulb. Can I use the same ballast in this unit for other bulbs like: Metal Halide, HPS, etc.
well... to be completely honest NO! there is 2 bad things that could amount to and i dont think you would like either 1) roast 30 dollar light bulbs / melt your ballest 2) burn down your home. if you dont mind either of them then By all means go for it. you have to have everything rated the same in HID if the ballest calls for a 250 watt HPS light then that is all you can use if you use a 250 watt MH you will have problems. a 175 watt MV is not the same as a 175 MH so you can not run them in the same ballest.